Case Number : CT0086 Adam_Bates

Marginal zone lymphoma
 

MZL

Agree, Marginal zone lymphoma. The infiltrate extends to the subcutaneous tissue and is composed of lymphocytes, plasmacytoid cells and plasma cells. There´s an amyloid-like substance at the superficial dermis.
The age and localization, neck, also favors MZL.

Dermal and subcutaneous nodular infiltrate composed of medium-sized lymphocytes showing cleaved nucleus and pale cytoplasm, admixed with plasma cells and lymphoplasmacytoid cells. Despite sparing the epidermis, a lymphoepithelial lesion involving an eccrine duct is shown on picture #4.
Agree with my colleagues' diagnosis of primary cutaneous marginal-zone B-cell lymphoma.

I agree, MZL is the most likely diagnosis (although this case appears less infiltrative than other cases I have seen). Mixed population as described, with expected absence of tingible-body macrophages in these images. No reactive or neoplastic follicular centers.

For the sake of expanding our differential diagnosis, other considerations:
1. Diffuse-pattern variant of follicular center lymphoma (FCL)...either primary or secondary to skin... may be virtually indistinguishable from MZL. Both may show prominent lymphoplasmacytic differentiation and poorly formed or absent follicles. Staining may be similar in tough cases, especially if numerous reactive T-cells obscure interpretation.
2. Pseudolymphoma.

Stains may help. Top on my list should be Ig light-chain stains to determine lambda/kappa light chain ratio on the plasmacytoid componen

Just to say something different what about angilymphoid hyperplasis with eosinophilia vs Kimura.
 

I would also add plasmacytoma to the differential.
 

Marginal zone lymphoma. There was kappa predominance by immunohistochemistry.